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Discussion of the WikiProject Chemistry - Please add your comment and discussion here. Older discussions are archived.

Shortcuts

This discussion page is about the Chemistry project itself, for detailed, in-depth discussions about specific topics, you'd be best served at the talk page of the specific subject, e.g., Chemicals, Chemical infoboxes, etc. There is also an image request page which might be of interest to you.

Wanted articles on chemical compounds

If anyone is looking to create new chemical compound articles, there are many listed in this November 2012 report on red links within articles tagged under WikiProject Medicine. I thought it might be of interest. Thanks. Biosthmors (talk) 22:47, 30 November 2012 (UTC)[reply]

I think the number of red links are more of a measure of how bloated some templates are rather than a measure of how "wanted" those articles are. :/ ChemNerd (talk) 19:05, 3 January 2013 (UTC)[reply]

Oxidation number and oxidation state shouldn't these be merged

Hello again, I have been reading the two articles, Oxidation number and Oxidation state and trying to make sense of them for a young but confused student.

The articles seem to start from the IUPAC definition then fall between two stools- the IUPAC definitions and the contradictory inorganic text book and exam board definitions. IUPAC defines oxidation state with a set of rules but text books define something almost identical as oxidation number. IUPAC says oxidation number relates to coodination chemistry, with a different rule from their oxidation state definition for the apportioning of electrons , but text books say oxidation number is synonymous with oxidation state and are quiet on the coordination chemistry angle. So after much well intentioned editing driven by the contradiction between what is taught and what IUPAC define, both articles have ended up as being full of good information but are confusing.

I suggest that Oxidation number and Oxidation state are merged and the main emphasis is on the text book / exam board definitions (which follow IUPAC oxidation state definition- but with some local differences) and a note that IUPAC define oxidation number differently and give some meaningful coordination chemistry examples. If they aren't merged I believe that eventually well intentioned editing will occur again and we'll be back at the current position.

I suspect during my long absence from Wikipedia this will have been discussed and that some folk may have views so I am putting it up here first. I am also starting to hear bees in my bonnet whispering about the Phosphite article but I'll address that ne another day. Axiosaurus (talk) 10:29, 19 December 2012 (UTC)[reply]

The two terms are different, the classic example being osmium tetroxide (OsO4), where the osmium has an oxidation number of VIII but clearly can't have the same oxidation state as this would imply a stable 8+ charge (just checked and it's wiki page and it has this wrong). It's an issue of whether the coordination is ionic or covalent. When it's ionic then the oxidation state and number will likely be the same, where it’s covalent then they likely won’t. It is easy to see how the two terms can be confused, the difference is subtle - but I'd argue it is important. As such I don't think they should be merged but a clear and prominent explanation of the differences is needed and should be present on both pages Project Osprey (talk) 11:29, 19 December 2012 (UTC)[reply]
That is an interesting take on oxidation number/state. I would be interested to know which text book says that and where that idea is taught as that may need to go into the article.Axiosaurus (talk) 14:04, 19 December 2012 (UTC)[reply]
Oh god, that's going back a few years. I'm not sure I can help you find a text book but I may be able to help with the article overall. What’s been written there isn’t strictly speaking wrong but... well, it’s just awful. It also seems to have resulted in confusion in a number of pages on transition metal complexes. Once the oxidation number page is fixed it may be necessary to review all of these pages and correct any errors. My problem however, is that I'm working on a re-write already, does anyone know if it's possible to have 2 sandboxes? Project Osprey (talk) 10:01, 20 December 2012 (UTC)[reply]

Proposed changes for three articles on Si-O chemistry

Big changes have been proposed by me in two large topics in organosilicon chemistry. No articles would disappear and the changes should help specialized and general readers alike, but since these topics are of high visibility, it is useful to serve notice lest other editors have suggestions.

  • Propose to refocus Siloxane into an article about the Si-O-Si functional group. The main compounds that have siloxane functional groups are silicones ([R2SiiO]n]). The difference between siloxane polymers and silicone polymers is a source of confusion, even by experts. Some content would migrate from siloxane to silicones with appropriate "see also's" on both sides. We would then build up the discussion of the synthesis, structures, and reactions of Si-O-Si groups within Siloxane.
  • Propose to change Silanol into an article on the functional group Si-O-H. Silanols are hugely important to surface science people, and it seems that we owe this readership an article on this critical functional group. Retained within the revised article would be a section on the parent species SiH4-x(OH)x. What we need is a good discussion of synthesis, structures, and reactions of Si-OH groups.

Suggestions or disagreements are welcome.--Smokefoot (talk) 18:56, 31 December 2012 (UTC)[reply]

Nonmetal categories

In WP:ELEMENTS we have been having a long-running discussion, here, about how we categorize the nonmetals. At the moment we have the following categories:

  • Other nonmetals
  • Halogens
  • Noble gases

Partly the discussion was started to see if the term 'other nonmetals' could be dispensed with or improved upon.

We are now looking at a proposal to change the categories to:

  • Reactive nonmetals
  • Noble gases

The current discussion about this proposal has now come down to whether or not to have one category of reactive nonmetals (as shown above) or two, for example:

  • Reactive nonmetals
  • Highly reactive nonmetals
  • Noble gases

There is a table here, which shows the eight proposals that have been presented to date for categorizing the non-noble nonmetals.

Your comments would be gratefully appreciated. Sandbh (talk) 21:36, 1 January 2013 (UTC)[reply]

Organometal “logos”

We have several “logos” in articles on organometal compounds. This may be problematic, because a lay reader may understand that e.g. C–Pb is an actual molecule. Opinions? --Leyo 18:57, 3 January 2013 (UTC)[reply]

What an interesting perspective. I just installed such a logo on siloxane. My own feeling is that the risk of confusion is offset by the advantages to summarizing a topic quickly to chemists. Taking the potential problem to the extreme, I cannot foresee negative consequences of a few people holding in their mind that Pb-C is an organolead compound. --Smokefoot (talk) 00:06, 4 January 2013 (UTC)[reply]
I would prefer if you added 6× an R to the image in Siloxane. This would avoid any potential confusion IMO. --Leyo 09:12, 4 January 2013 (UTC)[reply]

Request for feedback

I recently made a reversion to Dissociation constant. Could someone let me know if I should have done so, or revert what I have done if I should not have? It seems to me that the content does not fit the article as being very specific to a particular branch of research, but I would like to be double-checked. --Izno (talk) 16:42, 13 January 2013 (UTC)[reply]

I took a look at the talk page but didn't see any comments by you about the reversion, so I'll post my response here. I think the reversion was warranted. The "TCR" information, in my opinion, deserves its own page and could be mentioned on the page, but in my experience with chemical pedagogy, I don't think it fit the page well at all. Do you think we should leave a comment on the talk page so that the author knows why the reversion was done? Sean Egan(talk) 20:57, 18 January 2013 (UTC)[reply]
I've no objection to leaving a comment. --IznoRepeat (talk) 21:05, 18 January 2013 (UTC)[reply]

Periodic Table: proposed rename (move) from group 3 element to group 3 &tc, and periods alike

Originally from WP:ELEMENTS. See Talk:Group_3_element#Requested_move for a central discussion. -DePiep (talk) 21:08, 15 January 2013 (UTC)[reply]

Willard Gibbs

Hi. I've been working for a while on the bio. of Josiah Willard Gibbs. First, I'd like to mention that I think the article should be rated as of Top Importance in both chemistry and physics, and High Importance in math (it's currently High/High/Mid). It has often been pointed out that Gibbs essentially created modern physical chemistry (see the article for references). As a theoretical physicist he coined the term "statistical mechanics" and gave use the key concepts of the microcanonical, canonical, and grand canonical ensembles. And as a mathematician we owe him the concept of the cross product, the formulation of vector calculus in terms of div, grad, curl, and all that, and many of the ideas of what later became convex analysis.

My other concern is that I'd like to attract other editors who might want to edit and improve the article. Last Nov. I nominated it for FA. It got significant support, but some of the FA review regulars kept asking for independent copyediting and in the end the discussion just stalled and was archived. Gibbs's work as a theoretical scientist is extremely interesting and important, and I think his wikibio deserves more attention. - Eb.hoop (talk) 23:41, 17 January 2013 (UTC)[reply]

Alkyl-lead

I have redirected Alkyl-lead to Organolead compound. Is that cool? -- Alan Liefting (talk - contribs) 02:16, 25 January 2013 (UTC)[reply]

Cetrimonium bromide

Should the section Genomic DNA Isolation from plants by modified CTAB method be removed completely? --Leyo 09:24, 25 January 2013 (UTC)[reply]

Overcategorisation?

Check the subcategories within Category:Phenolic compounds in food. Plasmic Physics (talk) 07:58, 26 January 2013 (UTC)[reply]

TAFI

Hello,
Please note that Salt (chemistry), which is within this project's scope, has been selected to become a Today's Article for Improvement. The article is currently in the TAFI Holding Area, where comments are welcome about ideas to improve it. After the article is moved from the holding area to the TAFI schedule, it will appear on Wikipedia's Main Page in the "Today's Article for Improvement" section for one week. Everyone is invited to participate in the discussion and encouraged to collaborate to improve the article.
Thank you,
TheOriginalSoni (talk) 11:11, 26 January 2013 (UTC)[reply]
(From the TAFI team)

Typography question: italicize atomic-orbital subshells?

Should the labels associated with Azimuthal quantum numbers--"s", "p", "d", etc.--and the X-ray analogs--"K", "L", "M", etc.--be set in italic or plain text? Our articles that use them are not consistent, and even in the articles about the topics themselves. DMacks (talk) 03:13, 27 January 2013 (UTC)[reply]

Finally found it in ACS Style Guide (6th ed). Explicitly says roman-type for both cases. Should this be noted in Wikipedia:Manual of Style/Text formatting? DMacks (talk) 03:17, 27 January 2013 (UTC)[reply]
You can put it in WP:MOSCHEM? --Rifleman 82 (talk) 16:11, 27 January 2013 (UTC)[reply]

Naming of functional groups × free "radicals" × functional families

Hi, I need suggestions for a nomenclature problem. Please forgive the boring long explanation below.
I have been working on methylene and related articles. There are three fairly common meanings for the word:

(1)the free molecule :CH
2, officially called "carbene";
(2)the 'terminal' functional group =CH
2, connected to a single atom by a double bond;
(3)the 'bridging' functional group -CH
2-, connected to two different atoms by single bonds.

Until recently there was one article called [[methylene]] for sense (1), with chembox and everything, that briefly mentioned senses (2) and (3); and a page called [[methylenes]] that was basically a disambiguation page (only a couple of lines for each sense) but not tagged as such.
Now there are separate pages for senses (2) methylene group and (3) methylene bridge. Those pages are only stubs now but I believe that there is enough material to write books on them (bond geometry, electronic structure, reactions, spectroscopy, etc.)
There is also a methylene (disambiguation), that can be reached via the link "for other uses see..." in [[methylene]].
Then I went through almost all links to [[methylene]] and [[methylenes]] to resolve them to the proper page. Of ~130 links, I found 91 that were actually for the bridge, 22 for the terminal group, about 10 (lost the exact count) that were indeed for the free molecule, and 5 that I could not figure out (Cyclophane Johnson–Corey–Chaykovsky reaction Organoselenium chemistry Persistent carbene Tröger's base).
So it seems that

(A) as long as the article on the molecule is called just [[methylene]], we can expect that ~90% of the [[methylene]] links that will be created in the future by busy or lazy editors will be wrong. The reader who clicks on the link because he doesn't know the term will be quite confused; and since experts will not click there, the link will never be corrected. My conclusion: the article about the molecule must be renamed to a more specific name.
(B) Renaming [[methylene bridge]] to be just [[methylene]] would be convenient and result in correct link in ~70% of the cases. However, perhaps 30% of the new links may still end up pointing to the wrong sense of the word. My conclusion: neither sense should be the "primary" sense.
(C) The remaining alternative is to let [[methylene]] be the disambiguation page. Then new links [[methylene]] created by busy or lazy editors will end up pointing to a disamb page. This sounds bad, but such links can be detected by bots and will soon get fixed. Misdirected links will not.

I hope this plan is OK. Note that there are already two articles for CH3, methyl group and methyl radical. My question is what to call the current [[methylene]] article (about the molecule). Here are some ideas:

(a) [[Methylene radical]]. This would follow the precedent of [[Methyl radical]]. Unfortunately "radical" my mean "bound group", so the confusion would continue.
(b) [[Methylene (free radical)]]. Very clear and unambiguous, and fits Wikipedia general rules. However, I have been told that "radical" is now defined by the IUPAC and depends on spin state, and :CH
2 does not qualify. Is it so?
(c) [[Methylene molecule]] Never used in Wikipedia for any other page on chemical species.
(d) [[Methylene (molecule)]] Ditto.
(e) [[Methylene (carbene)]] This would be doubly correct since methylene is a carbene and also "carbene" is its quasi-official name. But in Wikipedia one does not call articles [[name (another name)]]. Also that title would be obscure to many readers and editors.
(f) Carbene Very correct, but unfortunately it is taken by the carbene family
(g) [[Methylene (chemical species)]] Too long, and maybe obscure to editors.

Any other suggestions? My favorite is (b) [[Methylene (free radical)]]. If "radical" is OK for methyl, why not for methylene? IUPAC be damned!
What do you say? All the best, --Jorge Stolfi (talk) 03:35, 29 January 2013 (UTC)[reply]

How about Methylidene for the carbene molecule, Alkylidene for the double bonded functional group, and Methylene to redirect to methane.
Alkylidene is chosen as it encompasses all doubly bonded alkane functional groups (ethylidene, propylidene, butylidene, etc.). Plasmic Physics (talk) 04:16, 29 January 2013 (UTC)[reply]
I think that all of the content on methylene should be combined into one article that deals the various meanings. I fear that talented editors sometimes force semantics upon readers. If some of the suggestions above are followed, otherwise cohesive and realitively simple concepts will be splintered in order to be highly precise. So I hope that we can drop some precision that us pointy headed types think about and serve readers vs our fetishes. --Smokefoot (talk) 10:21, 29 January 2013 (UTC)[reply]
That is fiddle-faddle, we have many articles on functional groups, as well as the corresponding radicals, eg. Hydroxyl v.s. Hydroxyl radical. Plasmic Physics (talk) 11:14, 29 January 2013 (UTC)[reply]
  • Well, the concepts *are* quite distinct, and there is much to be said about each one that has is irrelevant for the other two. Merging back would result in one messy article that will frustrate readers and editors alike. (Imagine combining pipe (fluid conveyance) and pipe (smoking) into one pipe article. Think of the reader who follows the link in the sentence "Pipes often burst in cold winters".)
    By the way, there is already a section in Substituent that lists all possible CHn functional groups, with their IUPAC nomenclature. So, any info that is common to both groups =CH2 and -CH2- could go there, together with similar info about -CH3, ≡CH, =CH-, etc.. (Perhaps that section should be split to [[methane substituents]], but that is another discussion.) However, that section (or any section/article with more than one CH2 meaning) would not satisfy the needs of readers and editors that need the link "[[methylene]]", as in "step III adds a methylene to the main ring".
    This last example shows that splitting the topics is not just pedantism: the meaning of the text changes completely depending on which "methylene" the link points to, and readers who follow the link will be quite confused and frustrated if the target describes both. That happened to me on the 5 articles above. --Jorge Stolfi (talk) 16:36, 29 January 2013 (UTC)[reply]
I'd support separate pages for the 'carbene' and 'methylene bridge' aspects with a disambiguous for 'methylene' on its own. I am, however, confused by Methylene_group, is this not just a Vinyl_group?Project Osprey (talk) 12:16, 30 January 2013 (UTC)[reply]
I understand that (as functional groups) methylene is =CH
2, vinyl is -(CH)=CH
2. Thus every molecule that has a vinyl also has a methylene (and a methine -(CH)=), but not the other way around. See methylpropene. (Is this correct?) --Jorge Stolfi (talk) 12:30, 30 January 2013 (UTC)[reply]
Ah! Well in that case it all seems good to me Project Osprey (talk) 12:41, 30 January 2013 (UTC)[reply]

Descriptors r and s

Pentane-2,3,4-triol (see structure and stereochemistry on p. 397) with all OH groups up is named (2R,3r,4S)-pentane-2,3,4-triol by ChemBioDraw. Granisetron is an another example that has an r in its IUPAC name. It seems that there is no reference to r (and s, which is the counterpart) in the Gold Book. The rule is described under Cahn–Ingold–Prelog priority rules#Stereocenters: R/S (last paragraph), but no reference is cited. Does anyone know of a quotable publication? --Leyo 16:54, 29 January 2013 (UTC)[reply]

"BASIC TERMINOLOGY OF STEREOCHEMISTRY (IUPAC Recommendations 1996)" says:
r,s -- Stereodescriptors of pseudo-asymmetric atom. For references see under R, S.
with those later references as:
R.S. Cahn, C.K. Ingold and V. Prelog, Angew. Chem. 78,413-447 (1966), Angew. Chem. Internat. Ed. Eng. 5 , 385-415, 511 (1966); and V. Prelog and G. Helmchen,Angew. Chem. 94,614-631 (1982), Angew. Chem Internat. Ed. Eng. 21,567-583 (1982).
"RULES FOR THE NOMENCLATURE OF ORGANI CHEMISTRY. SECTION E: STEREOCHEMISTRY (RECOMENDATIONS 1974)" says:
Pseudoasymmetric atoms. A sub-rule decrees that R groups have preference over S groups and this permits pseudoasymmetric acid, as in Cab(c-R)(c-S') to be treated in the same way as chiral centres; but as such a molecule is achiral (not optically active) it is given the lower-case symbol r or s.
DMacks (talk) 18:00, 29 January 2013 (UTC)[reply]
Thanks a lot! I found these publications online: p. 2214, p. 29. Based on your information, I found out that I just did not have the right keyword for searching the Gold Book. There actually is an entry:
  • IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "pseudo-asymmetric carbon atom". doi:10.1351/goldbook.P04921
I added this reference to Cahn–Ingold–Prelog priority rules#Stereocenters: R/S. Would it be worth drawing (2R,3r,4S)-pentane-2,3,4-triol or another compound with r or s (which one?) as an illustrative example? --Leyo 22:22, 29 January 2013 (UTC)[reply]
(1R,2s,3S)-1,2,3-trichlorocyclopentane
I drew (1R,2s,3S)-1,2,3-trichlorocyclopentane since it might be one of the easiest possible examples. --Leyo 13:26, 31 January 2013 (UTC)[reply]

Proposed rewrite of head section in "radical (chemistry)"

Hi again. I felt tempted to rewrite the head section of radical (chemistry) to make it a bit more accessible to non-chemists, but maybe I got the concept wrong. Would please someone have a look at this draft and comment on it? Many thanks... --Jorge Stolfi (talk) 02:08, 30 January 2013 (UTC)[reply]

RfC input needed

Input would be appreciated at an RfC regarding the Nobel prize in Chemistry. --Noleander (talk) 18:56, 5 February 2013 (UTC)[reply]

Wikidata: phase II live

Since phase II (infoboxes) of Wikidata is now live, there is a need to define the implementation for chemistry articles. There is currently a just draft: d:Wikidata:Infoboxes task force/terms#Chemistry / Chemie / Chimie. --Leyo 20:19, 5 February 2013 (UTC)[reply]

Chemistry education

There has been a merge tag on General chemistry proposing it be merged to Chemistry education for nearly a year, with only one comment at Talk:Chemistry education#Merge of General chemistry and that in the last day. Could we resolve this before the year anniversary comes up on 24 February? --Bduke (Discussion) 21:11, 6 February 2013 (UTC)[reply]

Charles Tanford (Cross-posted to WT:MCB and WT:Chemistry)

Looks like this article has been somewhat neglected. I happened to notice it was tagged with a "ref improve" tag, so I turned to the most logical source for citations.. the Protein Science "In Memoriam" article from 2009. Unfortunately, it appears that much of the current page is copied verbatim from the "In Memoriam" article. Tanford's a pretty significant figure in protein chemistry, so it would probably be worth expanding the article beyond just being a carbon copy of the obituary. Does anyone have time to work on such an expansion? Thanks. (+)H3N-Protein\Chemist-CO2(-) 18:33, 10 February 2013 (UTC)[reply]

Wikidata

Wikidata is still under construction (there is no possibility to add values, text or references right now) but there is a big interest to prepare the elements which will be useful for chembox , elements or others data consumers in WP. If there people who are interested to work in that kinf of project, feel free to have a look here. Biglama (talk) 19:40, 13 February 2013 (UTC)[reply]

Creation of a task force for chemical topic: here Biglama (talk) 15:08, 14 February 2013 (UTC)[reply]

Alkyl merger

We need to close a merger discussion at talk:alkyl#merger proposal. Plasmic Physics (talk) 03:51, 14 February 2013 (UTC)[reply]

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